fossil

Petrified Wood

Silicified Wood (Permineralized organic tissue)

Hardness: 6.5 to 7 on the Mohs scale; Color: Brown, grey, black, red, yellow; Luster: Vitreous to dull; Crystal structure: Microcrystalline quartz (chalcedony/opal); Cleavage: None

Hardness: 6
Color: Brown, grey, black, red, yellow
Luster: Vitreous to dull

Identified August 5, 2026More fossil →

Explore Petrified Wood in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6.5 to 7 on the Mohs scale; Color: Brown, grey, black, red, yellow; Luster: Vitreous to dull; Crystal structure: Microcrystalline quartz (chalcedony/opal); Cleavage: None

Formation & geological history

Formed when buried wood is slowly replaced by minerals (usually silica, quartz, or opal) over millions of years, often in ancient floodplains or volcanic ash beds during the Mesozoic and Cenozoic eras.

Uses & applications

Used for ornamental objects, polished display specimens, lapidary art, bookends, and jewelry making.

Geological facts

Petrified wood retains the original cellular structure of the tree while turning completely to stone, sometimes preserving tree rings and bark details microscopic in precision.

Field identification & locations

Look for visible wood grain and bark texture combined with a heavy stone weight and glass-like hardness that can scratch glass. Commonly found in deserts, badlands, and regions with ancient volcanic activity.

Other fossil specimens

See all

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil

Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

sedimentary

Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary

Crinoid Stem Fossils (Indian Beads / St. Cuthbert's Beads)

Crinoid columnal ossicles (phylum Echinodermata)

fossil

Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

fossil

Fossiliferous Limestone

Limestone with embedded fossil cross-section

sedimentary